The timely diagnosis and optimal management of hemostatic dysfunction in trauma and surgical patients is challenging due to the unavailability of suitable analytical tools. The current need to conduct multiple tests with multiple blood samples on multiple devices to ascertain the specific nature of the hemostatic defect by examining the different platelet aggregation and coagulation pathways is time consuming and cumbersome. Constrained by the time-critical nature of treating a bleeding patient, clinicians are often forced to use unguided, generic transfusion algorithms that may be sub-optimal for some patients. An on-site hemostasis analyzer that rapidly provides a broadly instructive report on multiple platelet and coagulation functions on a unified platform from a single blood sample on a single cartridge tested on a single device at the point-of-care has the potential to shift the guided blood product transfusion paradigm. To address this compelling need, the applicants have developed a hemostasis analyzer with a multichamber cartridge that can simultaneously assess multiple platelet aggregation and coagulation pathways from a single blood sample in less than 5 minutes. This cartridge interfaces with a base unit containing optoelectronic modules to detect and quantify platelet aggregation and clotting times in whole blood. The data from the instrument can be integrated into the patient's electronic health record that can be accessed by different clinicians to track the patient's hemostatic recovery trend. The goal of the proposed feasibility studies is to demonstrate that the novel hemostasis analyzer can reliably and reproducibly assess the status of platelet and coagulation functions in normal and hemostatically deficient blood. Platelet aggregation induced by adenosine di-phosphate (ADP), Collagen, and Arachidonic acid, and coagulation assessed by prothrombin time, activated partial thromboplastin time, and thrombin time will be measured in a 6-chamber cartridge. Sensitivity of the analyzer to coagulopathy will be tested by using clotting factor deficient blood in vitro and by testing blood from patients taking warfarin. Sensitivity of the analyzer to platele dysfunction will be tested by using blood from patients taking aspirin and ADP-receptor blockers (e.g. clopidogrel). Platelet function and clotting times of blood from trauma patients before and after restoration of hemostatic function will also be tested. For comparison, platelet aggregation and clotting times will be tested using conventional clotting time analyzers and platelet aggregometers. The expected outcome of this proof-of-concept phase of the project is the demonstration that multifactorial hemostatic function and deficiencies in specific hemostasis pathways can be rapidly assessed in the novel single platform system, paving the way for commercial development of a hemostasis analyzer that will facilitate guided transfusion of blood products to trauma and surgical patients.